Acute and chronic effects of cannabinoids on effort-related decision-making and reward learning: An evaluation of the cannabis `amotivational' hypotheses

Journal article


Lawn, Will, Freeman, Tom P., Pope, Rebecca A., Joye, Alyssa, Harvey, Lisa, Hindocha, Chandni, Mokrysz, Claire, Moss, Abigail, Wall, Matthew B., Bloomfield, Michael A. P., Das, Ravi K., Morgan, Celia J. A., Nutt, David J. and Curran, H. Valerie 2016. Acute and chronic effects of cannabinoids on effort-related decision-making and reward learning: An evaluation of the cannabis `amotivational' hypotheses. Psychopharmacology. 233 (19-20), pp. 3537 - 3552. https://doi.org/10.1007/s00213-016-4383-x
AuthorsLawn, Will, Freeman, Tom P., Pope, Rebecca A., Joye, Alyssa, Harvey, Lisa, Hindocha, Chandni, Mokrysz, Claire, Moss, Abigail, Wall, Matthew B., Bloomfield, Michael A. P., Das, Ravi K., Morgan, Celia J. A., Nutt, David J. and Curran, H. Valerie
Abstract

Rationale: Anecdotally, both acute and chronic cannabis use have been associated with apathy, amotivation, and other reward processing deficits. To date, empirical support for these effects is limited, and no previous studies have assessed both acute effects of Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), as well as associations with cannabis dependence. Objectives: The objectives of this study were (1) to examine acute effects of cannabis with CBD (Cann + CBD) and without CBD (Cann-CBD) on effort-related decision-making and (2) to examine associations between cannabis dependence, effort-related decision-making and reward learning. Methods: In study 1, 17 participants each received three acute vaporized treatments, namely Cann-CBD (8 mg THC), Cann + CBD (8 mg THC + 10 mg CBD) and matched placebo, followed by a 50 % dose top-up 1.5 h later, and completed the Effort Expenditure for Rewards Task (EEfRT). In study 2, 20 cannabis-dependent participants were compared with 20 non-dependent, drug-using control participants on the EEfRT and the Probabilistic Reward Task (PRT) in a non-intoxicated state. Results: Cann-CBD reduced the likelihood of high-effort choices relative to placebo (p = 0.042) and increased sensitivity to expected value compared to both placebo (p = 0.014) and Cann + CBD (p = 0.006). The cannabis-dependent and control groups did not differ on the EEfRT. However, the cannabis-dependent group exhibited a weaker response bias than the control group on the PRT (p = 0.007). Conclusions: Cannabis acutely induced a transient amotivational state and CBD influenced the effects of THC on expected value. In contrast, cannabis dependence was associated with preserved motivation alongside impaired reward learning, although confounding factors, including depression, cannot be disregarded. This is the first well powered, fully controlled study to objectively demonstrate the acute amotivational effects of THC.

Keywordscannabis; cannabinoids; THC; cannabidiol; motivation; reward; effort-related decision-making; reinforcement learning; addiction
Year2016
JournalPsychopharmacology
Journal citation233 (19-20), pp. 3537 - 3552
PublisherSpringer Verlag
ISSN0033-3158
Digital Object Identifier (DOI)https://doi.org/10.1007/s00213-016-4383-x
Scopus EID2-s2.0-84984820490
Open accessOpen access
Page range3537 - 3552
Research GroupSchool of Philosophy
Publisher's version
License
Place of publicationGermany
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